Numerous polymer-based medical devices have been developed for the delivery of therapeutic agents to the body. In accordance with some delivery strategies, a therapeutic agent is provided within a polymeric region of a medical device (e.g., a polymeric layer overlying a medical device substrate). Once the medical device is placed at the desired location within a patient, the therapeutic agent is locally released from the medical device to achieve a site-specific effect. As a result of this localized delivery, significantly lower doses therapeutic agent are used than would otherwise be required in connection with a systemic administration scheme (e.g., administration via an oral or parenteral route). In using lower doses, unwanted or even toxic side effects of significant systemic concentrations of therapeutic agent can often be avoided.
Methods have been described for loading polymeric regions of medical devices with therapeutic agents. For example, U.S. Pat. No. 6,545,097 to Pinchuk et al., which is incorporated herein by reference in its entirety, describes a method in which a therapeutic agent is dissolved in a solvent, and the resulting solution contacted with a polymeric region of a medical device, such that the therapeutic agent is loaded (e.g., by leaching/diffusion) into the same. For this purpose, the polymeric region can be immersed or dipped into the solution, or the solution can be applied to the polymeric region, for example, by spraying. The polymeric region can subsequently be dried, with therapeutic agent remaining therein.
Highly solvented mixtures have been used for many years in the automotive industry. For example, processes are known in which a solvent-only spray is directed to the edges of an area that has been repainted during the course of automotive repair. As a result, the paint is resolvated in place and the spray edges are blended with the prior coat, thus reducing or eliminating the need from polishing the edges. As another example, it is desirable in the automotive industry to cause metal flakes to stand on edge, thereby achieving the greatest light reflectance from the flakes. To achieve this goal, techniques are sometimes used in which the surface of a freshly painted panel is first softened using a solvent-only spray, after which a mixture of metal flakes and solvent is sprayed at high velocity onto the softened panel. Surface wetness can be controlled by altering the distance from the sprayer to the panel, which is an important process parameter, as the metal flake will not stand on edge if the surface is too wet and will not properly penetrate if the surface is too dry. The surface is then allowed to dry for a short period, securing the metal flakes in place. The surface then receives a so-called “clear coat” to protect the metal flakes from oxidation and to increase surface durability.